The disclosure relates generally to a power generation system and more specifically to systems and methods for controlling acceleration of power generators in the power generation system.
Typically, in island mode or off-grid applications, power generators may be coupled to an island grid that supports one or more customer loads. In one embodiment, these power generators may operate without being parallel coupled to a utility grid. Traditionally, the power generators are limited to diesel generators. However, in recent years, a growth in the use of gas generators for one or more applications has occurred due to tighter emission requirements and improving capabilities of gas engines.
During off-grid operation, a gas engine has generally less transient load acceptance and rejection capability than a diesel engine. Moreover, depending on the type and rating of a gas engine, load rejection may be a challenge. Large load rejections may cause the generators to accelerate and run at over speed, which in turn may lead to tripping the generators. Thus, when large load rejections occur, it is desired to control rapid acceleration of the power generators to avoid tripping the generators.
Various techniques may be employed to overcome the issue of rapid acceleration of power generators in an island-mode or off-grid operation. One proposed solution is to improve the transient capabilities of the power generators through advanced engine control concepts. Although such robust control systems have been developed and implemented, there are still certain limits to the amount of load rejection which small generators can handle only with such advanced controllers.
Another possibility is to increase the inertia of the generator set, for example by adding a flywheel or simply using oversized generators, to reduce the generator acceleration. This however results in additional weight and cost, which may also reduce the dynamic performance of the generators.
Hence, there is a need for an improved system and method for controlling the acceleration and speed of the power generators.